One of the major constraints to most vegetables growers in South Africa is related to water management and water use efficiency. This problem has added to the already enormous problem of drought in the country (Sedibe, 2003). Consequently, it is extremely important for growers to know the exact amount of water required for their crops to get exceptional yields of high quality. Achieving this will support vegetable growers in saving extra costs on water and hence increase their profits (Chartzoulakis and Drosos, 1995; Sedibe, 2003).
Drip irrigation is a localized technology that supplies water and dissolved nutrients directly to the roots of crops. This improves photosynthetic capacity of plants, maximizing yield, minimizing water usage, and reducing environmental pollution (Abdelraouf et al., 2013). Unlike other irrigation methods, drip irrigation conserves more water, and provides high levels of uniformities and application efficiencies. A number of studies in various crops have validated the positive effects of drip irrigation in improving crop yields (Ertek et al., 2006; Sezen et al., 2006; Vázquez et al., 2006). The global demand for nutrition is on the increase and the only means to meet such demand is to increase crop yield by improving the photosynthetic efficiency of plants. Plant biomass production is directly dependent on the net photosynthetic rate (Sing et al., 2013). Photosynthesis is the process by which photosynthetically active radiation (within the wavelength range 400–700 nm) is used in the presence of chlorophyll to synthesis carbohydrate such as sugar from CO2 and water (Petela, 2007). Photosynthetic rate (A), intercellular CO2 concentration (Ci), gS, transpiration rate (e), and dry matter production of plants are closely linked processes, which are usually influenced by water availability to plant.
Photosynthesis is proportional to gS, which plays a pivotal role in regulating the net CO2 uptake during abiotic stress (Haworth et al., 2011). Elevated gS favor carboxylation efficiency of RubisCO, but can lead to higher rates of water loss and associated risk of desiccation and xylem embolism, in addition to metabolic costs of enhanced construction of stomatal complexes (Cornic, 2000; Haworth et al., 2011).
Water deficiency is one of the most critical abiotic stresses that affect plant physiology and development (Gueta-Dahan et al., 1997). Limited water supply not only reduces chlorophyll content in plants, but also leads to poor growth and subsequently reduce crop yield (Anjum et al., 2003; Begun and Paul, 1993; Mafakheri et al., 2010; Moran et al., 1994; Younis et al., 2000; Zayed and Zeid, 1997). Previous studies have shown that fruit size and yield in crops supplied with adequate amount of water increase significantly compared with crops exposed to limited quantities (Kumar et al., 2007; Mao et al., 2002; Zeng et al., 2009).
Cucumber (C. sativus) is an economically important vegetable that is widely cultivated throughout the world. Cucumber has several nutritional values as functional food, possess high antioxidant properties as well as high mineral content (Chu et al., 2002). Cultivation of cucumbers often suffers setbacks from biotic and abiotic stresses during the whole development life cycle, which lead to reduction in yield and quality. Glasshouse soilless growers have expressed concern that water quantity may be suboptimal for plant growth.
South Africa is faced with extended drought conditions, which pose a big threat to crop growers in the country and there is need to adopt new and effective technology for optimal crop yield and efficient management of the limited available water. Therefore, understanding the optimum water regimen required for the optimum growth of cucumber plants in a drip irrigation system is essential. This study was aimed to investigate the effect of drip irrigation technique on plant growth and physiological parameters as well as crop yield in C. sativus under controlled glasshouse conditions.
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